Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09D133/062—Copolymers with monomers not covered by C09D133/06
  • C09D133/066—Copolymers with monomers not covered by C09D133/06 containing -OH groups

Definitions

• the present invention relates to the use of hydroxy-functional copolymers in aqueous coating compositions, such as color and paper coating compositions, to reduce the VOC content while maintaining the freeze/thaw stability of these compositions.
• Color coating compositions such as latex paints are employed for a variety of applications, including interior and exterior applications, and flat, semigloss, and gloss applications.
• latex paints which exhibit effective film formation it is common to add coalescents to them.
• coalescents are 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (i.e., TEXANOL®, available commercially from Eastman Chemical) and 2-ethylhexyl benzoate (i.e., VELATE® 378, available commercially from Vesicol Corporation).
• latex paints comprise antifrost agents, so that the paint can be used even after frost exposure.
• the antifrost agents generally also increase the open time for latex paints.
• examples of antifrost agents are ethylene glycol, diethylene glycol, and propylene glycol. A detailed discussion of these antifrost agents is found in “Antifreezes”, Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A3, pages 23-31.
• VOCs volatile organic compounds
• EP 1 106 660 describes a resin composition for an aqueous paint that comprises emulsion particles with a different phase structure, the emulsion particles with different phase structure having an external phase containing 1% to 20% by weight of an ethylenically unsaturated monomer having at least one polyethylene glycol chain and/or polypropylene chain.
• Hydroxyfunctional comonomers are used preferentially as dispersive or reactive polymer components.
• JP 2002-234904 describes freeze/thaw-stable wood glues which comprise up to 10% of a hydrolyzed polyvinyl alcohol protective colloid and also hydroxyethyl (meth)acrylate and hydroxypropyl acrylate as a dispersive component.
• hydroxy-functional comonomers examples include U.S. Pat. No. 4,539,363 (2-stage polymers with up to 30% of hydroxy monomer in the outer shell as crosslinker component) and JP 11-124508 (latex comprising vic-diol groups as room-temperature-reactive side groups). In these cases it is the reactivity of the alcohol function with respect, for instance, to epoxides, carboxylic acids or isocyanates that is exploited.
• JP 2004-059622 does mention the use of hydroxyethyl acrylate as a normal comonomer in a core/shell polymer which is used as a low-VOC binder
• the required freeze/thaw stability is provided by the incorporation of a hydrophilic monomer containing sulfonic acid groups or amide groups and/or polyethylene oxide or polypropylene oxide chains into the hard outer shell.
• U.S. Pat. No. 3,309,331 describes the reaction of a carboxylate-functional latex with aziridines. This leads to the functionalization of the polymer chain with 2-aminoethyl esters or 2-hydroxyethyl amides, respectively; to implement the freeze/thaw stability property 0.3%-10% of nonionic emulsifier is used.
• the functional moieties C are either open-chain or cyclic structures.
• Open-chain structures satisfy the general formula —(CHOH) n —H; n in this case is preferably 1-5, more preferably 1-2.
• the group of the spacers B for open-chain moieties C comprises —O—CH2-, —O—CHCH3-, —O—CH2-CH2-O—CH2-, O—CH2-CHCH3-O—CH2- or —O—CHCH3-CH2-O—CH2-, —X—C(O)— with X ⁇ O, NH, —O—CH2-CH2-X—C(O)—, O—CH2-CHCH3-X—C(O)— or —O—CHCH3-CH2-X—C(O)—, —O—CH2-C(CH3)(CH2OH)—, —O—CH2-C(CH2CH3)(CH2OH)—, —O—CH2-C(CH2OH) 2 —.
• Cyclic structures C derive from sugars which are in the furanose
• cyclic structures C there is no need to use the spacer B—i.e., the polymerizable moiety A is attached directly to C.
• the group of the spacers B for cyclic moieties C comprises —O—CH2-CH2-, O—CH2-CHCH3- or —O—CHCH3-CH2-, and —O—CH2-C(O)—.
• Suitable hydroxy-functional comonomers of the formula (I) are hydroxyethyl (meth)acrylate, glycerol (meth)allyl ether, glycerol mono(meth)acrylate, sorbitol mono(meth)acrylate, trimethylolpropane monoallyl ether, trimethylolpropane mono(meth)acrylate, pentaerythritol mono(meth)acrylate, 2-methacryloyloxyethylglucopyranoside, allyl-glucopyranoside, and acyloylgalactopyranoside.
• glycerol monomethacrylate (Blemmer® GLM) and glycerol monoacrylate.
• inventive amount of hydroxy-functional comonomer is between 1% and 10% (based on the total weight of the polymer), preferably 2-5%.
• freeze/thaw-stable coating compositions which in accordance with this invention include hydroxy-functional comonomers can be produced using a small amount of antifrost additives or even none at all.
• Aqueous coating compositions of the invention include less than 3% (based on the total weight of the aqueous composition), preferably less than 1% by weight, of antifrost agents. Particular preference is of course given to that case in which the coating composition is virtually free from antifrost agents.
• coating compositions produced in accordance with this invention comprise relatively low amounts of volatile organic compounds (VOCs) and are therefore more environmentally friendly.
• VOCs volatile organic compounds
• the invention further provides accordingly for the use of the comonomers of the general formula (I) for improved freeze/thaw stability of aqueous coating materials, particularly latex paints.
• the inventive hydroxy-functionalization of the polymer dispersion can be brought about by a variety of methods.
• GMA glycidyl methacrylate
• the latex polymer (a) used in the aqueous coating composition derives preferably from monomers which comprise at least one acrylic monomer from the group consisting of acrylic acid, acrylic esters, methacrylic acid, and methacrylic esters. Additionally the latex polymer may, if appropriate, one or more monomers from the group consisting of styrene, ⁇ -methylstyrene, vinyl chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, vinyl esters of branched tertiary monocarboxylic acids (e.g., vinyl esters available commercially under the trade name VEOVA® from Shell Chemical Company or sold under the designation EXXAR® Neo Vinyl Esters by ExxonMobil Chemical Company), dicarboxylic acids such as itaconic acid, crotonic acid, maleic acid, fumaric acid, and also their monoesters, and ethylene.
• monomers which comprise at least one acrylic monomer from the group consisting of
• conjugated C 4 -C 8 dienes such as 1,3-butadiene, isoprene, and chloroprene.
• the monomers preferably comprise one or more monomers from the group consisting of n-butyl acrylate, methyl methacrylate, styrene, and 2-ethylhexyl acrylate.
• the latex polymer is generally selected from the group consisting of straight acrylic resins (comprising as principal monomers acrylic acid, methacrylic acid, an acrylic ester and/or a methacrylic ester); styrene-acrylic resins (comprising as principal monomers styrene and acrylic acid, methacrylic acid, an acrylic ester and/or a methacrylic ester); vinyl-acrylic resins (comprising as principal monomers vinyl acetate and acrylic acid, methacrylic acid, an acrylic ester and/or a methacrylic ester); and acrylated ethylene-vinyl acetate copolymers (comprising as principal monomers ethylene, vinyl acetate, and acrylic acid, methacrylic acid, an acrylic ester and/or a methacrylic ester).
• the monomers may also comprise other principal monomers, such as acrylamide and acrylonitrile, and one or more functional monomers, such as acrylic acid, methacrylic acid, itaconic acid, acetylacetoxy ethyl methacrylate, and ureidomethacrylate, as will be readily apparent to the skilled worker.
• the latex polymer is a straight acrylic resin, such as a butyl acrylate/methyl methacrylate copolymer or an ethylhexyl acrylate/methyl methacrylate copolymer deriving from principal monomers comprising butyl acrylate, ethylhexyl acrylate, and methyl methacrylate.
• the latex polymer (a) of the invention comprising hydroxy-functional comonomer, can be used in the aqueous coating composition in combination with surfactants of the anionic, nonionic, cationic or amphoteric type, which are either polymerizable or nonpolymerizable.
• anionic surfactants include alkylbenzenesulfonic acids, sulfonated fatty acids, sulfosuccinates, fatty alcohol sulfates, alkylphenol sulfates, and fatty alcohol ether sulfates.
• nonionic surfactants examples include alkylphenol ethoxylates, primary alcohol ethoxylates, fatty acid ethoxylates, alkanolamide ethoxylates, fatty amine ethoxylates, EO/PO block copolymers, and alkylpolyglucosides.
• cationic and amphoteric surfactants use is made, for example, of the following: quaternized amine alkoxylates, alkylbetaines, alkylamidobetaines, and sulfobetaines.
• the polymer latex binder can be prepared by means of emulsion polymerization, by supplying monomers including at least one hydroxy-functional comonomer of the invention to a reactor in the presence of at least one initiator and at least one emulsifier as described below, and polymerizing the monomers to form the latex binder.
• the initiator may be any desired initiator known per se for use in emulsion polymerization, such as ammonium, sodium or potassium persulfate, or a redox system, which generally comprises an oxidant and a reductant. Customary redox initiator systems are described for example by A.S. Sarac in Progress in Polymer Science 24 (1999), 1149-1204.
• Suitable emulsifiers are found for example in Houben-Weyl, Methoden der organischen Chemie, volume XIV/1, Makromolekulare Stoffe [Macromolecular compounds], Georg Thieme Verlag, Stuttgart, 1961, pages 192 to 208.
• an initiator solution which comprises the initiator and water.
• at least one preliminary monomer emulsion is prepared which comprises at least a fraction of the monomers used to form the latex polymer, including the hydroxy-functional comonomer of the invention, one or more surfactants, water, and additional additives, such as NaOH.
• the initiator solution and the preliminary monomer emulsion are then fed continuously over a defined time period (1.5 to 5 hours, for example) into the reactor in order to bring the monomers to polymerization and so to prepare the latex polymer. It is preferred to add at least a fraction of the initiator solution to the reactor before the preliminary monomer emulsion is added.
• a seed latex in the reactor, such as a polystyrene seed latex.
• the purpose of using the seed latex is to give a uniform particle size distribution, and its use does not affect the freeze/thaw stability of the paint.
• water, one or more surfactants, and monomers not provided in the preliminary monomer emulsion can be placed in the reactor.
• the reactor is operated at an elevated temperature at least until all of the monomers have been added.
• the hydroxy-functionalized latex polymer of the invention is prepared in a two-stage process, as described in EP 710680, by using two different preliminary monomer emulsions, resulting in the formation of two polymer phases, a soft phase and a hard phase.
• the hydroxy-functional comonomer of the invention may be comprised in one or in both preliminary emulsions/phases; for maximum effect in relation to the freeze/thaw stability of the latex polymer, however, it should be copolymerized preferably in the soft phase.
• the polymer latex binder is preferably stripped chemically in order to reduce the residual monomer content.
• Chemical stripping takes place preferably by continuous addition of an oxidant, such as a peroxide (tert-butyl hydroperoxide, for example) and a reductant (sodium acetone bisulfite, for example), or of another redox duo, such as that of A.S. Sarac in Progress in Polymer Science 24 (1999), 1149-1204, for example, to the latex binder at an elevated temperature over a defined time period (0.5 hour, for example).
• the pH of the latex can then be adjusted and, following chemical stripping, a biocide or other additives can be added.
• VOCs volatile organic compounds
• the latex may be subjected as well to additional, physical stripping, as described for example in DE 19745580 or in EP 897931.
• the polymer dispersion comprising the above-described latex polymer (a) preferably has a solids content of about 30% to about 75% and an average latex particle size of about 50 to about 650 nm.
• the amount of the latex polymer in the aqueous coating composition is preferably about 5 to about 60 percent by weight and more preferably about 8 to about 40 percent by weight (i.e., the weight percentage fraction of the dry latex polymer, based on the total weight of the coating composition).
• the aqueous coating composition comprises at least one pigment.
• pigment comprises nonfilmforming solids such as pigments, extenders, and fillers.
• Said at least one pigment is selected preferably from the group consisting of TiO 2 (both in anatase form and in rutile form), clay (aluminum silicate), CaCO 3 (both in comminuted form and in precipitated form), alumina, silica, magnesium oxide, talc (magnesium silicate), barites (barium sulfate), zinc oxide, zinc sulfite, sodium oxide, potassium oxide, and mixtures thereof.
• Suitable mixtures include mixtures of metal oxides, such as those sold under the trade names MINEX® (oxides of silicon, aluminum, sodium, and potassium, available commercially from Unimin Specialty Minerals), CELITES® (alumina and silica, available commercially from Celite Company), ATOMITES® (available commercially from English China Clay International), and ATTAGELS® (available commercially from Engelhard).
• MINEX® oxides of silicon, aluminum, sodium, and potassium
• CELITES® alumina and silica, available commercially from Celite Company
• ATOMITES® available commercially from English China Clay International
• ATTAGELS® available commercially from Engelhard
• said at least one pigment comprises TiO 2 , CaCO 3 or clay.
• the average particle size of the pigments is generally in the range from about 0.01 to about 50 microns.
• the TiO 2 particles used in the aqueous coating composition generally have an average particle size of about 0.15 to about 0.40 micron.
• the pigment may be added to the aqueous coating composition in the form of a powder or a slurry. Within the aqueous coating composition the pigment is present preferably in an amount of about 5 to about 50 percent by weight, more preferably about 10 to about 40 percent by weight.
• the coating composition may if appropriate comprise additives, such as one or more film-forming assistants or coalescents.
• Suitable film-forming assistants or coalescents include plasticizers and drying retardants, such as high-boiling polar solvents.
• other conventional additives such as dispersants, additional surfactants (i.e., wetting agents), rheology modifiers, defoamers, thickeners, biocides, mildewcides, colorants such as color pigments and dyes, waxes, fragrances, cosolvents, and the like.
• nonionic and/or ionic e.g., anionic or cationic
• these additives are present generally in an amount of 0 to about 15% by weight, more preferably of about 1% to about 10% by weight, based on the total weight of the coating composition.
• the aqueous coating composition comprises less than 3.0% by weight of antifrost agent, based on the total weight of the aqueous coating composition.
• antifrost agents are ethylene glycol, diethylene glycol, propylene glycol, glycerol (1,2,3-trihydroxypropane), ethanol, methanol, 1-methoxy-2-propanol, 2-amino-2-methyl-1-propanol, and FTS-365 (a freeze/thaw stabilizer from Inovachem Specialty Chemicals).
• the aqueous coating composition comprises less than 1.0% by weight of antifrost agent or is largely free (i.e., comprises less than 0.1% by weight) of antifrost agent.
• the aqueous coating composition of the invention has a VOC content of preferably less than about 100 g/l and more preferably less than or equal to about 50 g/l.
• the aqueous coating compositions of the invention comprise little antifrost agent or none at all, the compositions possess freeze/thaw stabilities to levels which are desirable in the art.
• the aqueous coating compositions of the invention may be subjected to freeze/thaw cycles in accordance with ASTM Method D2243-82 without undergoing coagulation.
• the aqueous coating compositions can also pass a drawdown test carried out in accordance with the method discussed below.
• the aqueous coating compositions of the invention have good heat storage stability and, after 14 days' storage at 50° C. in accordance with the method discussed below, exhibit increases in Stormer viscosity of less than 15 KU, more preferably 10 KU or less.
• the remainder of the aqueous coating composition of the invention is made up of water. Although a large part of the water is present in the polymer latex dispersion and in other components of the aqueous coating composition, water is generally added separately as well to the aqueous coating composition.
• the aqueous coating composition comprises generally about 10% to about 85% by weight and more preferably about 35% to about 80% by weight of water. Expressed alternatively, the total solids content of the aqueous coating composition is generally about 15% to about 90% by weight, more preferably about 20% to about 65% by weight.
• the coating compositions are generally formulated in such a way that the dried coatings comprise at least 10% by volume of dry polymer solids and additionally 5% to 90% by volume of nonpolymeric solids in the form of pigments.
• the dried coatings may also comprise additives, such as plasticizers, dispersants, surfactants, rheology modifiers, defoamers, thickeners, biocides, mildewcides, colorants, waxes, and the like which do not evaporate when the coating composition dries.
• the aqueous coating composition is a latex paint composition which comprises a latex polymer (a) derived from at least one acrylic monomer selected from the group consisting of acrylic acid, arylic esters, methacrylic acid, and methacrylic esters and from at least one polymerizable hydroxy-functional comonomer C, at least one pigment, and water.
• a latex polymer derived from at least one acrylic monomer selected from the group consisting of acrylic acid, arylic esters, methacrylic acid, and methacrylic esters and from at least one polymerizable hydroxy-functional comonomer C, at least one pigment, and water.
• the present invention further comprises a process for preparing an aqueous coating composition by mixing a latex polymer (a) which derives from at least one monomer and at least one polymerizable, hydroxy-functional monomer, as described above, with at least one pigment.
• the latex polymer (a) is preferably in the form of a latex polymer dispersion.
• the additives can be added in any desired, appropriate order to the latex polymer, to the pigment or to combinations thereof.
• the aqueous coating composition has a pH of preferably 7 to 10.
• the aqueous coating composition is a stable fluid which can be applied to any of a wide variety of materials, such as, for example, paper, wood, concrete, metal, glass, ceramic, plastics, plaster, and roofing substrates such as asphalt coatings, roofing felts or polyurethane foam insulation; or to preliminarily coated, primed, undercoated, worn or weathered substrates.
• the aqueous coating composition of the invention can be applied to the materials by a variety of techniques which are well known per se, such as spreading, brushing, rolling, air-assisted spraying or airless spraying, electrostatic spraying and the like, for example.
• Example 1a describes the synthesis of a one-stage, nBA-based polymer dispersion containing 3% (weight percent based on dry polymer mass) of BLEMMER® GLM (glycerol monomethacrylate from Marubeni Speciality Chemicals, Düsseldorf, Germany).
• BLEMMER® GLM glycerol monomethacrylate from Marubeni Speciality Chemicals, Düsseldorf, Germany.
• BLEMMER® GLM possesses the following structure:
• a monomer emulsion is prepared which is composed of 248 parts of water, 42.9 parts of arylsulfonate (15% strength aqueous solution), 22.3 parts of BLEMMER® GLM (92% strength aqueous solution), 5.2 parts of methacrylic acid, 276 parts of methyl methacrylate, and 349 parts of n-butyl acrylate.
• To prepare the initiator solution 2.6 parts of ammonium persulfate were dissolved in 117 parts of water.
• a 1.5-liter glass reactor was charged with 236 parts of water, flooded with nitrogen, and heated to 78° C.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.6 parts of a 10% strength tert-butyl hydroperoxide solution and 4.6 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.9% and a particle size of 238 nm.
• Example 1b describes the synthesis of a one-stage, nBA-based polymer dispersion containing 5% (weight percent based on dry polymer mass) of BLEMMER® GLM.
• a monomer emulsion is prepared which is composed of 248 parts of water, 42.9 parts of arylsulfonate (15% strength aqueous solution), 35.5 parts of BLEMMER® GLM (92% strength aqueous solution), 5.2 parts of methacrylic acid, 276 parts of methyl methacrylate, and 336 parts of n-butyl acrylate.
• To prepare the initiator solution 2.6 parts of ammonium persulfate were dissolved in 117 parts of water.
• a 1.5-liter glass reactor was charged with 236 parts of water, flooded with nitrogen, and heated to 78° C.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.6 parts of a 10% strength tert-butyl hydroperoxide solution and 4.6 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 51% and a particle size of 279 nm.
• Example 1c describes the synthesis of a one-stage, nBA-based polymer dispersion containing 3% (weight percent based on dry polymer mass) of glycerol monoacrylate (laboratory product from BASF AG).
• Glycerol monoacrylate possesses the following structure:
• a monomer emulsion is prepared which is composed of 231 parts of water, 42.9 parts of arylsulfonate (15% strength aqueous solution), 39.0 parts of glycerol monoacrylate (50% strength aqueous solution), 5.2 parts of methacrylic acid, 276 parts of methyl methacrylate, and 349 parts of n-butyl acrylate.
• To prepare the initiator solution 2.6 parts of ammonium persulfate were dissolved in 117 parts of water.
• a 1.5-liter glass reactor was charged with 236 parts of water, flooded with nitrogen, and heated to 78° C.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.6 parts of a 10% strength tert-butyl hydroperoxide solution and 4.6 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 51% and a particle size of 240 nm.
• Example 1d describes the synthesis of a one-stage, nBA-based polymer dispersion containing 3% (weight percent based on dry polymer mass) of HEMA (hydroxyethyl methacrylate from Lonza AG).
• HEMA hydroxyethyl methacrylate from Lonza AG.
• a monomer emulsion is prepared which is composed of 250 parts of water, 42.9 parts of arylsulfonate (15% strength aqueous solution), 32.5 parts of HEMA, 5.2 parts of methacrylic acid, 276 parts of methyl methacrylate, and 336 parts of n-butyl acrylate.
• To prepare the initiator solution 2.6 parts of ammonium persulfate were dissolved in 117 parts of water.
• a 1.5-liter glass reactor was charged with 236 parts of water, flooded with nitrogen, and heated to 78° C. When the polymerization temperature had been reached, 10% of the initiator solution and 1% of the monomer emulsion were added and initial polymerization was carried out for 20 minutes.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.6 parts of a 10% strength tert-butyl hydroperoxide solution and 4.6 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.5% and a particle size of 314 nm.
• Example 2a describes the synthesis of a one-stage, EHA-based polymer dispersion containing 3% (weight percent based on dry polymer mass) of BLEMMER® GLM.
• a monomer emulsion is prepared which is composed of 229 parts of water, 39.6 parts of arylsulfonate (15% strength aqueous solution), 19.7 parts of BLEMMER® GLM (92% strength aqueous solution), 4.8 parts of methacrylic acid, 282 parts of methyl methacrylate, and 295 parts of 2-ethylhexyl acrylate.
• arylsulfonate (15% strength aqueous solution
• BLEMMER® GLM 92% strength aqueous solution
• methacrylic acid 282 parts of methyl methacrylate
• 295 parts of 2-ethylhexyl acrylate To prepare the initiator solution, 2.4 parts of ammonium persulfate were dissolved in 108 parts of water.
• a 1.5-liter glass reactor was charged with 217 parts of water, flooded with nitrogen, and heated to 78° C.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.4 parts of a 10% strength tert-butyl hydroperoxide solution and 4.2 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.7% and a particle size of 294 nm.
• Example 2b describes the synthesis of a one-stage, EHA-based polymer dispersion containing 5% (weight percent based on dry polymer mass) of BLEMMER® GLM.
• a monomer emulsion is prepared which is composed of 229 parts of water, 39.6 parts of arylsulfonate (15% strength aqueous solution), 32.8 parts of BLEMMER® GLM (92% strength aqueous solution), 4.8 parts of methacrylic acid, 282 parts of methyl methacrylate, and 283 parts of 2-ethylhexyl acrylate.
• To prepare the initiator solution 2.4 parts of ammonium persulfate were dissolved in 108 parts of water.
• a 1.5-liter glass reactor was charged with 217 parts of water, flooded with nitrogen, and heated to 78° C.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.4 parts of a 10% strength tert-butyl hydroperoxide solution and 4.2 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 51% and a particle size of 229 nm.
• Example 2c describes the synthesis of a one-stage, EHA-based polymer dispersion containing 3% (weight percent based on dry polymer mass) of glycerol monoacrylate BLEMMER® GLM.
• a monomer emulsion is prepared which is composed of 213 parts of water, 39.6 parts of arylsulfonate (15% strength aqueous solution), 36.0 parts of glycerol monoacrylate (50% strength aqueous solution), 4.8 parts of methacrylic acid, 282 parts of methyl methacrylate, and 295 parts of 2-ethylhexyl acrylate.
• To prepare the initiator solution 2.4 parts of ammonium persulfate were dissolved in 108 parts of water.
• a 1.5-liter glass reactor was charged with 217 parts of water, flooded with nitrogen, and heated to 78° C.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.4 parts of a 10% strength tert-butyl hydroperoxide solution and 4.2 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.7% and a particle size of 275 nm.
• Example 3 describes the synthesis of a two-stage polymer dispersion comprising 3% (weight percent based on dry polymer mass) of BLEMMER® GLM.
• a first monomer emulsion is prepared which is composed of 187 parts of water, 24.0 parts of Disponil FES 77 (30% strength aqueous solution of a sulfated fatty acid ethoxylate, from Cognis Deutschland), 32.0 parts of Steinapol NLS (15% strength aqueous solution of sodium lauryl sulfate), 19.7 parts of BLEMMER® GLM (92% strength aqueous solution), 6.0 parts of acrylic acid, 3.0 parts of itaconic acid, 45 parts of Mhoromer 6844-0 [N-(2-methacryloyloxyethyl)ethyleneurea, 25% in MMA, from Röhm, Darmstadt, Germany], 141 parts of methyl methacrylate, and 315 parts of n-butyl acrylate.
• a second monomer emulsion which is composed of 43 parts of water, 6.0 parts of Disponil FES 77 (30% strength aqueous solution of a sulfated fatty acid ethoxylate, from Cognis Deutschland), 8.0 parts of Steinapol NLS (15% strength aqueous solution of sodium lauryl sulfate), and 72 parts of methyl methacrylate.
• the initial solution was prepared by dissolving 1.2 parts of ammonium persulfate in 23 parts of water.
• a 1.5-liter glass reactor was charged with 240 parts of water and 29.1 g of a polystyrene seed latex (33% form, approximately 25 nm), flooded with nitrogen, and heated to 85° C.
• the polymerization temperature had been reached, 5% of the initiator solution were added and initial polymerization was carried out for 5 minutes. Thereafter the first monomer emulsion was metered in at a uniform rate over the course of 150 minutes and the remainder of the initiator solution over the course of 180 minutes; immediately after the end of addition of the first monomer emulsion, the second is metered in over a period of 30 minutes, followed by polymerization at 85° C. for 30 minutes.
• a chemical deodorization was carried out by supplying the reaction mixture with 6.0 parts of a 10% strength tert-butyl hydroperoxide solution and 6.4 parts of a 16.5% strength acetone bisulfite solution simultaneously over a period of 60 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.5% and a particle size of 132 nm.
• Comparative Example 1 describes the synthesis of a one-stage, nBA-based polymer dispersion without hydroxy-functional comonomers.
• a monomer emulsion is prepared which is composed of 248 parts of water, 42.9 parts of arylsulfonate (15% strength aqueous solution), 5.2 parts of methacrylic acid, 276 parts of methyl methacrylate, and 369 parts of n-butyl acrylate.
• To prepare the initiator solution 2.6 parts of ammonium persulfate were dissolved in 117 parts of water.
• a 1.5-liter glass reactor was charged with 236 parts of water, flooded with nitrogen, and heated to 78° C. When the polymerization temperature had been reached, 10% of the initiator solution and 1% of the monomer emulsion were added and initial polymerization was carried out for 20 minutes.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.6 parts of a 10% strength tert-butyl hydroperoxide solution and 4.6 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.8% and a particle size of 251 nm.
• Comparative Example 2 describes the synthesis of a one-stage, EHA-based polymer dispersion without hydroxy-functional comonomers.
• a monomer emulsion is prepared which is composed of 229 parts of water, 39.6 parts of arylsulfonate (15% strength aqueous solution), 4.8 parts of methacrylic acid, 282 parts of methyl methacrylate, and 315 parts of 2-ethylhexyl acrylate.
• To prepare the initiator solution 2.4 parts of ammonium persulfate were dissolved in 108 parts of water.
• a 1.5-liter glass reactor was charged with 217 parts of water, flooded with nitrogen, and heated to 78° C. When the polymerization temperature had been reached, 10% of the initiator solution and 1% of the monomer emulsion were added and initial polymerization was carried out for 20 minutes.
• a chemical deodorization was carried out by supplying the reaction mixture with 2.4 parts of a 10% strength tert-butyl hydroperoxide solution and 4.2 parts of a 5.7% strength Rongalit® C solution (BASF) simultaneously over a period of 40 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.8% and a particle size of 300 nm.
• Comparative Example 3 describes the synthesis of a two-stage polymer dispersion without hydroxy-functional comonomers.
• a first monomer emulsion is prepared which is composed of 189 parts of water, 24.0 parts of Disponil FES 77 (30% strength aqueous solution of a sulfated fatty acid ethoxylate, from Cognis Deutschland), 32.0 parts of Steinapol NLS (15% strength aqueous solution of sodium lauryl sulfate), 6.0 parts of acrylic acid, 3.0 parts of itaconic acid, 45 parts of Mhoromer 6844-0 [N-(2-methacryloyloxyethyl)ethyleneurea, 25% in MMA, from Röhm, Darmstadt, Germany], 141 parts of methyl methacrylate, and 333 parts of n-butyl acrylate.
• a second monomer emulsion which is composed of 43 parts of water, 6.0 parts of Disponil FES 77 (30% strength aqueous solution of a sulfated fatty acid ethoxylate, from Cognis Deutschland), 8.0 parts of Steinapol NLS (15% strength aqueous solution of sodium lauryl sulfate), and 72 parts of methyl methacrylate.
• the initial solution was prepared by dissolving 1.2 parts of ammonium persulfate in 23 parts of water.
• a 1.5-liter glass reactor was charged with 240 parts of water and 29.1 g of a polystyrene seed latex (33% form, approximately 25 nm), flooded with nitrogen, and heated to 85° C.
• the polymerization temperature had been reached, 5% of the initiator solution were added and initial polymerization was carried out for 5 minutes. Thereafter the first monomer emulsion was metered in at a uniform rate over the course of 150 minutes and the remainder of the initiator solution over the course of 180 minutes; immediately after the end of addition of the first monomer emulsion, the second is metered in over a period of 30 minutes, followed by polymerization at 85° C. for 30 minutes.
• a chemical deodorization was carried out by supplying the reaction mixture with 6.0 parts of a 10% strength tert-butyl hydroperoxide solution and 6.4 parts of a 16.5% strength acetone bisulfite solution simultaneously over a period of 60 minutes. After the reaction mixture had cooled to room temperature, a pH of approximately 8 was set using concentrated ammonia. The resultant polymer dispersion had a solids content of 50.6% and a particle size of 135 nm.
• Hydroxyethylcellulose thickener from Hercules Inc. 2) BK Ladenburg, Ladenburg, Germany 3) Sodium salt of a carboxylated polyelectrolyte, 25% strength aqueous solution, pigment dispersant from Rohm & Haas Co.
• Stormer viscosity (in KU, Krebs Units): Stormer viscosities were measured in accordance with ASTM D 562-81.
• ICI viscosity (in Poise) ICI viscosities were measured at high shear rates in accordance with ASTM D 4287-94.
• Hot storage stability the hot storage stability of the paints was determined by measuring the increase in Stormer viscosity ( ⁇ KU) after 14-day storage in a drying cabinet at 50° C.
• Freeze/thaw stability the freeze/thaw stability of the paints was measured in accordance with ASTM D 2243-82 with a freezing cabinet temperature of ⁇ 18° C. Where there was no coagulation, the Stormer viscosity of the sample was measured after each freeze/thaw cycle.

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